--- /dev/null
+/FLOPPY DISK (RX01,RX71) NON-SYSTEM HANDLER FOR OS/8
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+/COPYRIGHT (C) 1977 BY DIGITAL EQUIPMENT CORPORATION
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+/THE INFORMATION IN THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE
+/AND SHOULD NOT BE CONSTRUED AS A COMMITMENT BY DIGITAL EQUIPMENT
+/CORPORATION. DIGITAL EQUIPMENT CORPORATION ASSUMES NO RESPONSIBILITY
+/FOR ANY ERRORS THAT MAY APPEAR IN THIS DOCUMENT.
+/
+/THE SOFTWARE DESCRIBED IN THIS DOCUMENT IS FURNISHED TO THE PURCHASER
+/UNDER A LICENSE FOR USE ON A SINGLE COMPUTER SYSTEM AND CAN BE COPIED
+/(WITH INCLUSION OF DIGITAL'S COPYRIGHT NOTICE) ONLY FOR USE IN SUCH
+/SYSTEM, EXCEPT AS MAY OTHERWISE BE PROVIDED IN WRITING BY DIGITAL.
+/
+/DIGITAL EQUIPMENT CORPORATION ASSUMES NO RESPONSIBILITY FOR THE USE
+/OR RELIABILITY OF ITS SOFTWARE ON EQUIPMENT THAT IS NOT SUPPLIED BY
+/DIGITAL.
+/
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+\f/FLOPPY DISK (RX01,RX71) NON-SYSTEM HANDLER FOR OS/8
+
+/DEFINITIONS OF RX8/E IOT'S
+
+RXVER= "E&77
+
+DEVCOD= 750 /DEVICECODE
+
+LCD= 6001+DEVCOD /LOAD COMMAND REGISTER
+XDR= 6002+DEVCOD /TRANSFER DATA REGISTER
+STR= 6003+DEVCOD /SKIP ON TRANSFER REQUEST FLAG, CLEAR FLAG
+SER= 6004+DEVCOD /SKIP ON ERROR FLAG, CLEAR FLAG
+SDN= 6005+DEVCOD /SKIP ON DONE FLAG, CLEAR FLAG
+INTR= 6006+DEVCOD /INTERRUPT ENABLE/DISABLE
+INIT= 6007+DEVCOD /INITIALIZE CONTROLLER AND RECALIBRATE DRIVES
+
+
+/NOTES ON THIS HANDLER:
+
+/THIS HANDLER READS AND WRITES THE DISK IN "12-BIT" MODE, IN WHICH
+/ONLY 6 BITS OF EVERY 8-BIT BYTE ARE USED. AN RX01 CARTRIDGE
+/CONTAINS 494 OS/8 BLOCKS UNDER THIS METHOD
+
+/TO MAXIMIZE SPEED ON THE DEVICE, THE HANDLER READS AND WRITES DATA
+/ON A TRACK WITH A TWO-WAY INTERLEAVE - I.E. RECORDS 1-26 ON A TRACK
+/ARE WRITTEN IN THE SEQUENCE:
+/ 1,3,5,7,9,11,13,15,17,19,21,23,25,2,4,6,8,10,12,14,16,18,20,22,24,26
+
+/IN THIS WAY THE HANDLER CAN TRANSFER DATA AT A 5KHZ WORD RATE
+
+/MODIFIED TO ALLOW ADDRESS CALCULATION DURING SECTOR BUFFER
+/LOAD-UNLOAD.
+\f *0 /ORIGIN FOR BUILD
+
+ -2 /TWO ENTRY POINTS
+ DEVICE RX01 /"RX01" IS THE GROUP NAME
+ DEVICE RXA0 /"RXA0" IS THE ENTRY POINT NAME
+ 4250 /DCB WORD - DEVICE TYPE 25, DIRECTORY DEVICE
+ RXA0&177 /ENTRY POINT OFFSET
+ 0 /THIS WORD ALWAYS SEEMS TO BE 0
+ 0 /UNUSED FOR NONSYSTEM DEVICE
+
+ DEVICE RX01 /"RX01" IS THE GROUP NAME
+ DEVICE RXA1 /"RXA1" IS THE ENTRY POINT NAME
+ 4250 /DCB WORD - DEVICE TYPE 25, DIRECTORY DEVICE
+ RXA1&177 /ENTRY POINT OFFSET
+ 0 /THIS WORD ALWAYS SEEMS TO BE 0
+ 0 /UNUSED FOR NONSYSTEM DEVICE
+\f *200 /HANDLER CODE
+
+BUF, 0 /USER BUFFER POINTER
+REC, 0 /RX01 RECORD NUMBER BEFORE INTERLEAVING
+BC, 0 /BLOCK COUNT OF TRANSFER
+FN, 0 /FUNCTION, 0=WRITE, 2=READ
+TRANS, 0 /TRANSFER COMMAND
+
+FLPWC=. /100 COUNTER FOR SILO OK IN LDCMD ENTRY
+LDCMD, 0 /WAIT FOR DONE FLAG AND LOAD CMD REG
+ DCA TRANS /SAVE THE NEW COMMAND REG VALUE
+DONELP, TAD S7600 /SEE IF THE KEYBOARD BUFFER
+ KRS /CONTAINS A CONTROL/C CHARACTER
+ TAD (-7603 /(WITH OR WITHOUT PARITY)
+ CLL /KEEP LINK CLEAAR
+ SNA CLA
+ KSF /WITH THE FLAG UP.
+ JMP NOTCTC /IF NOT, CONTINUE
+SCDIF0, CDF CIF 0 /IF SO, RETURN TO OS/8
+ JMP I S7600
+
+NOTCTC, SDN /WAIT FOR THE DONE FLAG TO COME UP
+ JMP DONELP /BEFORE YOU LOAD THE COMMAND REGISTER
+ TAD TRANS /NOW GET THE NEW COMMAND REGISTER CONTENTS
+ LCD /AND LOAD IT.
+ SER /SKIP IF I/O ERROR
+ JMP I LDCMD /AND RETURN
+ CLA CLL CML RAR /SET AC TO 4000
+ JMP SRET /TAKE ERROR RETURN
+
+
+RXA0, RXVER /ENTRY POINT FOR UNIT 0
+ CLA /BE PROTECTIVE
+ JMP RXCOMN /GO TO COMMON CODE
+S70, 70 /** MUST BE AT 33 ON THIS PAGE**
+
+ IFNZRO S70&177-33 <.ERROR>
+
+MQ, /DIVIDE TEMPORARY
+RXA1, RXVER /ENTRY POINT FOR UNIT 1
+ CLA /CAREFUL, CAREFUL!
+ TAD RXA1
+ DCA RXA0 /PUT CALLING ADDR IN KNOWN PLACE
+ TAD DIVLP /GET "20"
+RXCOMN, TAD DIVRAL /SET AC TO 20*UNIT+4
+ DCA UNIT /SAVE UNIT NUMBER
+ RDF
+ TAD SCDIF0 /REMEMBER CALLING FIELD FOR RETURN
+ DCA SRET
+\f
+/ OVERALL COMMENTS:
+/
+/ LINK REMAINS 0 THROUGH THE MAIN PROCESSING LOOP
+/ EXCEPT AS MANIPULATED BY DIVSUB
+/
+/ OVERALL LOOP CONTROL THROUGH BC IS MILDLY ODD.
+/ BC STARTS WITH MINUS COUNT OF THE # OF WORDS TO BE TRANSFERRED.
+/ BC IS INCREMENTED 77 TIMES AT THE SILO CODE, AND 1 TIME AFTER
+/ THE I/O OPERATION.
+/ A READ OPERATION STARTS AND FINISHES AT THE MIDDLE OF THE LOOP.
+/ A WRITE OEPRATION STARTS AT THE TOP, AND FINISHES AT BOTTOM.
+/ THUS, A 1 BLOCK READ INCREMENTS 1, 77, 1, 77 AND EXITS FROM MIDDLE.
+/ AND, A 1 BLOCK WRITE INCREMENTS 77, 1, 77, 1 AND EXITS FROM BOTTOM.
+/
+/ DIVISION IS CARRIED OUT IN PARALLEL WITH I/O OPERATION BECAUSE OF
+/ TIMING CONSIDERATIONS OF THE VT78.
+/
+/ THERE IS NO ERROR RETRY, NOT PARTICULARLY CRITICAL FOR A FLOPPY.
+
+ CLL CML CLA RAR /SET LINK=0, AC=4000
+ TAD I SYS /TO PUT READ-WRITE BIT TO LINK
+S33, AND S70 /KEEP BITS FOR CDF
+ TAD SCDF0 /ADDING IN CDF LITERAL
+ DCA BUFCDF /CDF INSTRUCTION TO USER'S BUFFER
+ CML RTL /FUNCTION CODE, 0=WRITE, 2=READ
+ DCA FN
+ TAD I SYS /MAKE CONTROL COUNT
+ RAL
+ AND S7600 /MAKE CONTROL COUNT FOR TOTAL
+ CIA /NUMBER OF WORDS
+ DCA BC
+ ISZ SYS
+ TAD I SYS /FETCH BUFFER ADDRESS
+ DCA BUF
+ ISZ SYS
+ TAD I SYS /OS8 BLOCK #
+ CLL RTL /TIMES 4 TO BE FLOPPY SECTOR #
+ DCA REC
+ ISZ SYS /ERROR EXIT FROM I/O CALL
+ JMS DIVSUB /COMPUTE TRACK/SECTOR FOR FIRST I/O
+ TAD FN /READ OR WRITE START DIFFERENTLY
+ SZA CLA /SKIP ON WRITE
+ JMP STREAD /GO TO READ
+/
+/ WRITE FALLS THRU.......
+/
+\f/
+/
+/ TOP OF MAIN PROCESSING LOOP
+/
+SETSLO, TAD FN /SET SILO TO LOAD-UNLOAD DEPENDING
+ JMS LDCMD
+ TAD S7700 /SILO CONTROL COUNT 100 OCTAL
+ DCA FLPWC
+BUFCDF, HLT /CDF TO USER'S BUFFER PLACED HERE
+TRLOOP, TAD I BUF /FETCH A WORD IN CASE WRITE
+ STR /WAIT
+ JMP .-1
+ XDR /AC TO SILO; OR; SILO TO AC
+ DCA I BUF /PLACE A WORD IN CASE READ; WRITE REPLACES SAME.
+ ISZ BUF /MOVE TO NEXT BUFFER LOCATION (MAY SKIP)
+S77, 77 /LITERAL 77, EXECUTES AS A NOP
+ ISZ FLPWC /DONE WITH 100 OCTAL SILO OPERATION
+ JMP TRLOOP /NO
+ TAD BC /INCREMENT BC BY 77 HERE, 1 LATER
+ TAD S77 /CHECKING FOR A READ EXIT
+MAGIC, SNA /IF BC HAS GONE TO ZERO, NO-OP FOR LDCMD
+ JMP OKEX /READ EXIT.
+ DCA BC /REPLACING BC FOR WRITE EXIT CHECK AT LOOP END
+/
+/ MIDDLE OF MAIN PROCESSING LOOP
+/
+STREAD, TAD FN /READ STARTS HERE
+ TAD UNIT /SET UP DO DO READ OR WRITE I/O
+ JMS LDCMD
+ TAD MQ /LOAD PRECOMPUTED SECTOR INFO
+ STR
+ JMP .-1 /IN CASE NOT READY
+ XDR
+S7700, 7700 /CLEAR AC, CAN'T SKIP (XDR LEAVES AC ALONE)
+ TAD QUO /TRACK
+ STR /ILLEGAL 7700 ENTRY WILL HANG; THE FUNCTION
+ JMP .-1 /IS NOT SET UP (LDCMD)
+ XDR
+S7600, 7600
+ ISZ REC /MOVE TO NEXT FLOPPY SECTOR
+ JMS DIVSUB /COMPUTE NEXT TRACK AND SECTOR DURING THIS I/O
+ TAD MAGIC /WAIT FOR I/O TO COMPLETE
+ JMS LDCMD
+ ISZ BC /CHECK FOR WRITE EXIT
+ JMP SETSLO /NO, BACK TO TOP
+OKEX, ISZ SYS /BUMP TO REGULAR EXIT
+SRET, HLT /CDF CIF FOR USER'S CALLING FIELD
+ JMP I SYS /GONE
+/
+UNIT, 0 /UNIT
+SYS=RXA0
+/
+\f/
+/
+/ LITERALS
+/
+SM15, -15
+SCDF0, CDF 0
+/
+/ DIVSUB
+/
+/ MUST ENTER WITH LINK AND AC 0
+/ COMPUTES TRACK IN 'QUO', SECTOR IN 'MQ', FROM # IN 'REC'
+/
+/ REPEATED SUBTRACTS OF 13 DECIMAL LEAVE THE HIGH N-1 BITS OF
+/ QUOTIENT IN QUO, THE LOW BIT OF QUOTIENT IN LINK, AND THE
+/ REMAINDER IN AC. THE INTERLEAVE IS ACCOMPLISHED BY SHIFTING
+/ LOW QUOTINET BIT INTO LOW REMAINDER BIT.
+/
+DIVSUB, 0
+ DCA QUO /INIT QUOTIENT FOR DIVIDE
+ TAD REC /RECORD # MASSAGED IN AC
+DIVLP, SNL /LINK USAGE REVERSED FROM RICHIE'S CODE
+ ISZ QUO /ISZ EVERY OTHER TIME, <=DIVIDE BY 26
+ TAD SM15 /THE -13 DECIMAL
+ SMA /SKIP ON DONE
+ JMP DIVLP /MORE
+DIVRAL, RAL /LINK USAGE REVERSED; INTERLEAVE!!
+ TAD S33 /ADD 233 (200 IRREL) MAKING SECTOR
+ DCA MQ
+ JMP I DIVSUB /LEAVING LINK AND AC 0
+QUO, 0 /DIVIDE TEMP
+/
+
+ $
+
+\f
projects / pdp8.git / blobdiff